This invention relates to mixing devices commonly referred to as static mixers. Generally such mixers are disc-like in shape and include a plate having a central opening or orifice of various fixed geometric configurations and mounted in a pipe through which fluid passes so as to create a turbulent mixing action to the fluid such that other materials introduced into the stream generally via injection nozzles located downstream and generally adjacent the plate are uniformly mixed with the fluid.
As indicated, standard static mixers have a fixed geometry, which means that the headloss is a direct function of the velocity of the fluid in the pipeline. Generally speaking, a mixer designed for low (1-3 FPS) velocity will generate excessive headloss at high pipeline velocity (8-12 FPS). Conversely, a mixer designed for reasonable mixing and headloss at high velocity generally will not provide good mixing at low velocity.
To date, this problem has been addressed by making separate mixers with mixing characteristics suited for particular pipeline velocities. For instance, the present applicant commercially supplies three separate mixers with different orifice diameters or beta ratios (beta ratio=orifice diameter/pipe inside diameter) of 0.7, 0.8 and 0.9. See FIG. 9 for further beta information. This enables a user to choose a mixer that gives good mixing performance at high, medium or low pipeline fluid velocities respectively, but no one mixer achieves good performance at all of these different velocities.
It is therefore an object of the present invention to provide a mixer and mixing system that can be adjusted to achieve good mixing performance at differing pipeline velocities without the need of removing one mixer and substituting another mixer in the pipeline.
These and other objects of the invention are accomplished by the provision of a static mixer of the type having a generally centrally disposed orifice disposed within a generally flat plate adapted for mounting within a pipe such that the plate is adjustably movable to various alternate operable positions between a first essentially non-mixing position wherein the plate edge is disposed in line with the fluid flow within the pipe to a fully mixing position wherein the plate face is disposed normal to the fluid flow within the pipe.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.